1. Field of the Invention
The present invention relates generally to rotatable members for machines and, more particularly, to a rotatable assembly for a machine.
2. Description of the Related Art
It is known to provide a machine such as a waste processing machine to reduce waste material. The waste processing machine typically includes a rotatable assembly such as a rotor assembly. The rotor assembly generally includes a rotor and a plurality of processing tools attached to the rotor for reducing the waste material as the rotor rotates. An example of such a waste processing machine is disclosed in U.S. Pat. No. 5,863,003 to Smith. In that patent, the rotor assembly comprises a generally cylindrical rotor onto which a plurality of processing tools is mounted. The rotor is mounted to a coaxially disposed shaft by multiple plate-like braces extending tangentially from the outer surface of the shaft to the inner surface of the rotor. There are two sets of braces, and each set is attached at opposing ends of the rotor.
In operation, an engine operatively rotates the shaft, which causes the rotor to rotate. As waste material passes by the rotor, the processing tools attached to the rotor contact the waste material, cut or reduce the waste material, and expel the reduced waste material from the waste processing machine.
Rigid attachments, for example welds, join the individual braces to the rotor and shaft. When non-grindable materials, such as rocks and other hard debris, enter the waste processing machine, the processing tools are unable to break them down. Instead, when the processing tools impact the non-grindables, the impact force transfers through the rotor, through the braces, and into the shaft as a concentrated or shock load. More specifically, loading of the first and second sets of braces results in a torsional load and bending load in the same plane on the shaft. These combined loads can cause deformation or breakage of the drive end of the shaft, which renders it inoperable. Users can replace the shaft, but replacement typically costs a significant amount of money and machine downtime.
One attempt to solve this problem is to increase the diameter of the shaft. As such, the bulkier or larger diameter shaft can withstand higher stresses or concentrated loads, making it less likely to deform or break when the processing tools contact non-grindable material. However, the larger diameter shafts cost more to make, which is undesired. Moreover, increasing the diameter of the shaft does not ensure other components in the rotor assembly will withstand the high stresses caused by the non-grindables. For example, a belt typically drives the shaft during operation. When the processing tools impact the non-grindables, the resultant shock load may cause the belt to break, costing the user significant time and money for repair. Therefore, there is a need in the art for an assembly that can better withstand the high impact forces and concentrated loads.